BBC4 controller Richard Klein is jumping ship to ITV to be the rival broadcaster's director of factual, after nearly four and a half years running the channel.

ITV also announced on Tuesday that Helen Warner is joining as director of daytime.

Warner and Klein will join ITV in the summer, taking over responsibilities formerly handled by director of factual and daytime Alison Sharman, who left at the end of February after seven years at the company.

Klein will be working with Jo Clinton-Davis, who has been looking after Sharman's patch since her departure and has been promoted to the newly created role of controller of factual.

Klein's move follows his BBC4 budget being cut as part of the corporation's Delivering Quality First cost savings initiative.

The channel's critically acclaimed original drama and comedy output, which has included The Thick of It, was one of the main victims of the cuts.

Peter Fincham, the ITV director of TV, said: "He's been a highly successful controller of BBC4 and I know he's looking forward to a return to mainstream television and the challenge of making high quality programmes for broad audiences. ITV factual has scored some notable successes recently and Richard is exactly the right person to take it on to a new level. He and Jo Clinton-Davis will make a formidable team."

Klein said: "The ambition is to make programmes that people watch and talk about in equal measure, and that's a challenge I relish."

Warner is a former Channel 4 head of daytime who has previously worked as a programme-maker, editing This Morning and launching Loose Women.

Danny Cohen, the BBC director of TV, thanked Klein for his "very great contribution" to the corporation since joining in 1996 in an email to staff on Tuesday. He said Klein had helped make BBC4 "feel like a big place – a place that people talk about".

Cohen added that Klein would be leaving the BBC immediately, "because of obvious sensitivities" with him joining a rival broadcaster, and an acting BBC4 controller would be appointed.

Klein said in an internal BBC email: "I felt it was time for a change and a new challenge and so I have accepted a new job at ITV."

• To contact the MediaGuardian news desk email media@guardian.co.uk or phone 020 3353 3857. For all other inquiries please call the main Guardian switchboard on 020 3353 2000. If you are writing a comment for publication, please mark clearly "for publication".

• To get the latest media news to your desktop or mobile, follow MediaGuardian on Twitter and Facebook